Vacuum hydrastatic jar accelerator

ABSTRACT

A deep well energy storage tool for accelerating the action of a hydraulic jar providing a vertically shiftable piston on said tool and applying upwardly thereto, incidental to the tensioning and tripping of the jar, the hydrastatic pressure of a column of liquid occupying the drill string, while said piston is exposed to a vacuum thereabove.

United States Patent [1 1 Sutliff et al.

[ June 11, 1974 2,988,147 6/1961 Webb 175/297 X Primary ExaminerRobert L. Wolfe Assistant Examiner-Richard P. Tremblay [57] ABSTRACT A deep well energy storage tool for accelerating the action of a hydraulic jar providing a vertically shiftable piston on said tool and applying upwardly thereto, incidental to the tensioning and tripping of the jar, the hydrastatic pressure of a column of liquid occupying the drill string, while said piston is exposed to a vacuum thereabove.

2 Claims, 6 Drawing Figures VACUUM HYDRASTATIC JAR ACCELERATOR [76] Inventors: Wayne N. Sutliff; Jim L. Downen,

both of 2931 Pierce Rd., Bakersfield, Calif. 93308 [22] Filed: June 28, 1972 [21] Appl. No.: 266,977

[52] US. Cl 175/232, 175/296, 175/321 [51] Int. Cl E2lb 27/00, E2lb 1/10 [58] Field of Search 175/293, 296, 297, 299, 175/306, 232, 321; 166/178; 267/125 [56] References Cited UNITED STATES PATENTS 2,837,315 6/1958 Burns et a1 175/296 PATETEMMH m4 slalslssa SHEET 2 OF 2 VACUUM HYDRASTATIC JAR ACCELERATOR SUMMARY OF THE INVENTION The present invention is an improvement on the fishing tool energizers disclosed in our US. Pat. Nos. 3,472,326 and 3,539,026. The energy source employed in said patented tools was comprised in a series of metal springs which were compressed during the tensioning of the hydraulic jar with which the tool was associated so that when the jar tripped the energy stored in the springs would be released to impart a rapid upward acceleration of a series of drill collars assembled in the string between the jar and said tool.

Inasmuch as the use of springs in any deep well tool introduces operational and maintenance problems, it is the prime object of the present invention to provide a well jar accelerator operating on the vacuum vs. hydrastatic pressure principle and which will utilize the energy available at the bottom of a well in a column of liquid occupyingthe drill string.

It is another object of the invention to provide such a deep well jar accelerator which may be employed either in wet holes or approximately dry holes.

BRIEF DESCRIPTION OF THE DRAWINGS FIGS. 1, 2 and 3 comprise fragmentary vertical sectional views of successive sections of the invention and show the same with the parts thereof telescopically contracted as at the start of a jarring operational.

FIG. 4 is a cross sectional view taken on the line 44 of FIG. 1 and shows the annular piston area of the tool against which hydrastatic pressure is applied upwardly in accelerating the action of a deep well jar associated the internal mandrel through which operating fluid is introduced into the annular cylinder chamber of the tool.

FIG. 5 is a cross sectional view taken on the line 55 of FIG. 2 and illustrates the construction of the male spline sleeve of the invention.

FIG. 6 is a cross sectional view taken on the line 6-6 of FIG. 3 and illustrates the construction of the female spline sleeve of the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT Referring specifically to the drawings, the invention is there illustrated as incorporated in a well jar accelerator 10 which is secured, at its upper end to the lower end of a drill string 11, said accelerator having suspended from the lower end thereof a fishing tool assembly 12. The latter assembly is not illustrated in detail inasmuch as this is conventional and embraces in the order named downwardly from theaccelerator 10, one or more drill collars, a hydraulic jar and a fishing tool.

The accelerator 10 comprises an external tubular mandrel l3 and an internal tubular mandrel 14 which is slideably received within the external mandrel to allow a limited degree of extensibility of the accelerator.

The external mandrel l3 embraces an upper sub 15, a thin tubular external cylinder forming sleeve 16, a middle sub 17 and an external female spline sleeve 18.

35 with the tool, this view also showing the fluid ports in The upper sub is relatively long, its length being preferably approximately five times its external diameter, this sub providing at its upper end a pin box 19 for receiving the pin 20 on the lower end of drill string 11. The bottom of pin box 19 is provided with a short bore which connects with the upper end of a counterbore 26 which extends almost to the lower end of sub 15 where it connects with a relatively short bore 27 having an internal annular groove 28 for receiving an O-ring 29. The lower end portion 30 of upper sub 15 comprises an annular cylinder head and is externally turned down to provide threads 31, a shoulder 32, a smooth cylindrical surface 33 between the threads 31 and the lower end of the sub and an external annular groove 34 for receiving an O-ring 35. The tubular external cylinder forming sleeve 16 is internally threaded at its opposite ends, the upper end of this sleeve screwing onto the threads 31 and fitting snugly against the shoulder 32 of the upper sub 15. The O-ring 35 makes a fluid tight seal between annular cylinder head 30 and sleeve 16.

The middle sub 17 is turned down at its opposite ends to provide external threads and 41 and has a bore 42 and an annular internal O-ring groove 43 near its lower end for accommodating an O-ring 44. The upper end portion of middle .sub 17 is provided with a counterbore 45 for a purpose which will be made clear hereinafter.

The threads 40 on the upper end of middle sub 17 screw into the internal threads provided in the lower end of sleeve 16 and unite middle sub 17 with said sleeve. External female spline sleeve 18 isinternally threaded at its upper end and screws on to the threads 41 of middle sub 17 to unite said sleeve with said sub. As shown in FIG. 2, the spline sleeve 18 has a smooth bore 46 throughout the major upper portion thereof which terminates near the lower end of said sleeve (FIGS. 3 and 6) with a radial inwardly extending series of spline teeth 48.

The internal tubular mandrel 14 comprises a lower sub 49, a tubular internal cylinder forming'sleeve 50, an annular piston and a tubular internal vacuum cylinder forming sleeve 56.

The lower sub 49 has an internal bore 57 extending throughout its length, this having a threaded counterbore 58 in its lower end for receiving a seal disc 59 and a nut 60 for holding this in place. The seal disc 59 is provided externally with an O-ring 61 for forming a seal between said disc and bore 58. Formed externally on the lower end of sub 49 is a threaded pin 62 for connecting sub 49 for fishing tool assembly 12. Sub 49 is turned down to form a shoulder 63 from which a male spline sleeve 64 extends upwardly to form the balance of the sub 49. The sleeve 64 is provided with a circumferentially spaced series of external splines 65 which intermesh with the splines 48 of the female spline section 47 of the female spline sleeve 18. The upper end of sleeve 64 is internally counterbored and threaded to screw onto the externally threaded lower end of tubular internal cylinder forming sleeve 50. The latter sleeve has a smooth cylindrical outer surface which makes a 'slideable sealing engagement with O-ring 44 and the upper end of said sleeve is provided with external threads and, just below said threads has formed therein a pair of diametrically opposed slots 71 for a purpose to be made clear hereinafter.

The annular piston 55 has a short bore 72 which connects downwardly with an internally threaded counter .turned down to provide external threads 76 onto which an internally threaded packer compression nut 77 screws, said nut extending into and compressing a cup shaped packer 78 against said piston and expanding said packer so that it pressurally engages the smooth internal cylindrical surface of the external cylinder forming sleeve 16.

OPERATION As already noted, the drawings illustrate the parts of the accelerator in contracted relation to each other as at the moment of starting a jarring operation.'Such an operation of the accelerator 10 requires the presence of a body of liquid in the drill string 11. If the well hole itself isoccupied with such a liquid the seal disc 59 may be omitted inassemblying the tool as the well liquid inside and outside the drill string 11 will seek a common level so that this fluid within the drill string will be equal in depth to the fluid in the hole. This fluid flows through the slots 71 into the annular piston chamber 79 so as to fill this chamber.

The jarring operation starts with lifting the drill string 11 a sufficient distance to bring the middle sub 17 into engagement with the piston 55. This upward movement of the external mandrel 13 produces a vacuum in that portion of the annular piston chamber 79 disposed above the piston 55. The full hydrastatic pressure of the liquid column confined in the drill string 11 is at this time being applied through the slots 71 to that portion of the piston chamber 79 located below piston 55 and is thus imposed upwardly against said piston. This pressuremay vary from one to five or more tons, depending upon the diameter of the tool 10 and the height of the column of liquid in the drill string. The lifting on the drill string 11 continues after the middle sub 17 en-' gages the piston 55 so as to transmit a direct pull through the inner mandrel 14 to the fishing tool assembly 12. The jar in this assembly gradually yields to this pressure for a predetermined period of time, at the end of which the jar trips, allowing free movement for a short distance upwardly of the drill string 11 terminating in a resumption of the direct connection between the drillstring and the fishing tool assembly and imparting a sharp upward blow on the fish tending to release this from its stuck position which of course is the object of the jarring operation.

The accelerator 10 of the invention responds to the pressure of. the confined well fluid against the bottom end of piston 55 at the instant the jar trips to apply a sufficient upward fluid pressure on the inner mandrel 14 to cause a rapid upward movement of the drill collars embodied in the fishing tool assembly 12 and located between the tool 10 and the jar of said assembly so that when the free movement allowed by the jar is concluded and direct connection with the fish is reestablished, considerable momentum has been stored up in the substantialweight embodied in said drill collars so that these apply a hammer blow of substantial force to the fish which has been greatly augmented by the action of the accelerator 10.

Following a jarring action as above described,,the drill string 11 may be lowered to again contract the elements of the accelerator 10 as shown in the drawings so that the jarring action may be repeated as many times as necessary to secure the desired end. if operations are carried on in a wet hole, that is a well substantially filled with a liquid, such as rotary mud, the seal disc 59 is omitted from the accelerator. If such a disc is used, as when the hole outside the drill string is relatively dry, a go-devil can be dropped down the drill string after completion of the fish removing operation so as to penetrate the seal disc 59 and permit the escape downwardly of the liquid from the drill string 11 into the well hole.

It is to be noted that the packer 78 is a cup packing which functions merely in a downward direction and freely allows any liquid accumulating between the piston and the cylinder head 30 to escape downwardly past this packing eachtime the piston 55 is returned to its upward position in the annular chamber 79 as shown in the drawing.

The splined relation between the external and internal mandrels l3 and 14 provide constant torque transmitting relation between these mandrels throughout the various longitudinal relationships which these mandrels have to each other during the operation of the tool 10.

The counterbore 45 is provided in the upper endof the sub 17 to downwardly prolong annular chamber 79 and thus maintain communication between said chamber and passages 71 throughout the extension of the tool 10.

l. A well jar accelerator comprising:

a tubular internal mandrel terminating in a sub at it lower end and having an annular piston near its upper end;

a tubular external mandrel slideably enclosing said piston and internal mandrel and terminating in a sub at its lower end, said upper sub being provided for connecting the tool to a drill string, and said lower sub for connecting said tool to a fishing tool assembly including a jar, whereby said accelerator may be extended by lifting on said drill string and returned to normal contracted condition by lowering said drill string;

means forming an annular vacuum cylinder chamber in said external mandrel which is closed at its upper end and in which said piston makes a sealed sliding fit to produce an approximate vacuum therein, above said piston, when said accelerator is so extended;

means limiting the maximum extensibility of said accelerator, there being passage means accessible to the liquid confined within said drill string and said accelerator and communicating with said cylinder chamber beneath said annular piston whereby the hydrastatic pressure existing in said liquid may impinge upon the bottom of said piston to impart an upward thrust on said internal mandrel which is transmitted to said jar coincident with the extension of said accelerator and during the tensioning and tripping of said jar; and

a seal disc means provided in said lower sub for temporarily blocking the escape of fluid downwardly from said accelerator.

2. A well jar accelerator comprising:

a tubular internal mandrel terminating in a sub at its lower end and having an annular piston near its upper end;

a tubular external mandrel slideably enclosing said piston and internal mandrel and terminating in a sub at its upper end, said upper sub being provided for connecting the tool to a drill string, and said lower sub for connecting said tool to a fishing tool assembly including a jar, whereby said accelerator may be extended by lifting on said drill string and returned to normal contracted condition by lowering said drill string;

means forming an annular vacuum cylinder chamber in said external mandrel which is closed at its upper end and in which said piston makes a sealed sliding fit to produce an approximate vacuum therein, above said piston, when said accelerator is so extended;

means limiting the maximum extensibility of said accelerator, there being passage means accessible to the liquid confined within said drill string and said accelerator and communicating with said cylinder chamber beneath said annular piston whereby the hydrastatic pressure existing in said liquid may impinge upon the bottom of said piston to impart an upward thrust on said internal mandrel which is transmitted to said jar coincident with the extension of said accelerator and during the tensioning and tripping of said jar;

said cylinder chamber being closed at its upper end by a cylinder head formed by said upper sub and having a central bore provided with O-ring seal means; and

a tubular sleeve provided on said piston and slideably axially extending upwardly through said cylinder head to form an expansible vacuum chamber between said head, said piston, said sleeve and said external mandrel,

said internal mandrel including a smooth middle sleeve which connects said piston to said bottom sub, and wherein said bottom sub embodies a male spline sleeve to which said middle sleeve connects;

said external mandrel embodying a smooth bore middle sub having O-ring seal means which slideably receives said middle sleeve, and a female spline sleeve which slideably receives and meshes with said male spline sleeve to transmit torque between said mandrels;

said passage means being provided in said smooth middle sleeve near its upper end. 

1. A well jar accelerator comprising: a tubular internal mandrel terminating in a sub at it lower end and having an annular piston near its upper end; a tubular external mandrel slideably enclosing said piston and internal mandrel and terminating in a sub at its lower end, said upper sub being provided for connecting the tool to a drill string, and said lower sub for connecting said tool to a fishing tool assembly including a jar, whereby said accelerator may be extended by lifting on said drill string and returned to normal contracted condition by lowering said drill string; means forming an annular vacuum cylinder chamber in said external mandrel which is closed at its upper end and in which said piston makes a sealed sliding fit to produce an approximate vacuum therein, above said piston, when said accelerator is so extended; means limiting the maximum extensibility of said accelerator, there being passage means accessible to the liquid confined within said drill string and said accelerator and communicating with said cylinder chamber beneath said annular piston whereby the hydrastatic pressure existing in said liquid may impinge upon the bottom of said piston to impart an upward thrust on said internal mandrel which is transmitted to said jar coincident with the extension of said accelerator and during the tensioning and tripping of said jar; and a seal disc means provided in said lower sub for temporarily blocking the escape of fluid downwardly from said accelerator.
 2. A well jar accelerator comprising: a tubular internal mandrel terminating in a sub at its lower end and having an annular piston near its upper end; a tubular external mandrel slideably enclosing said piston and internal mandrel and terminating in a sub at its upper end, said upper sub being provided for connecting the tool to a drill string, and said lower sub for connecting said tool to a fishing tool assembly including a jar, whereby said accelerator may be extended by lifting on said drill string and returned to normal contracted condition by lowering said drill string; means forming an annular vacuum cylinder chamber in said external mandrel which is closed at its upper end and in which said piston makes a sealed sliding fit to produce an approximate vacuum therein, above said piston, when said accelerator is so extended; means limiting the maximum extensibility of said accelerator, there being passage means accessible to the liquid confined within said drill string and said accelerator and communicating with said cylinder chamber beneath said annular piston whereby the hydrastatic pressure existing in said liquid may impinge upon the bottom of said piston to impart an upward thrust on said internal mandrel which is transmitted to said jar coincident with the extension of said accelerator and during the tensioning and tripping of said jar; said cylinder chamber being closed at its upper end by a cylinder head formed by said upper sub and having a central bore provided with O-ring seal means; and a tubular sleeve provided on said piston and slideably axially extending upwardly through said cylinder head to form an expansible vacuum chamber between said head, said piston, said sleeve and said external mandrel, said internal mandrel including a smooth middle sleeve which connects said piston to said bottom sub, and wherein said bottom sub embodies a male spline sleeve to which said middle sleeve connects; said external mandrel embodying a smooth Bore middle sub having O-ring seal means which slideably receives said middle sleeve, and a female spline sleeve which slideably receives and meshes with said male spline sleeve to transmit torque between said mandrels; said passage means being provided in said smooth middle sleeve near its upper end. 